Renewable Energy - Wind Generation in Ireland

WIND GENERATION in Ireland has seen a dramatic increase in activity in recent years. In response ESB Networks has had to address new issues from both technical and administrative points of view. This article aims to give a flavour of the main aspects.

Background
Windfarms can range from 1 to 50 turbines, 0.5MW to 100MW with one connection to ESB. In general, turbines generate at 690V and this is transformed to 20kV for local distribution within the windfarm. For the smaller windfarms, connection can be made directly to the ESB distribution networks without further transformation. However for connection to 38kV or higher voltages, windfarm operators must provide their own substation with suitable transformation.

Renewable generators can be connected at a range of voltages, depending largely on the MW size and access to suitable network. Typically, generators will be connected as follows:

LV	<200kW
MV	200kW - 9MW
38kV	3MW- 25MW
110kV	>15MW

All connections at 38kV or less are distribution connections, while connections at 110kV can be either TSO or DSO offers.

Generally windfarms are completely unmanned except for routine maintenance visits. Most have sophisticated remote control systems to monitor performance, and this often done by the manufacturers in Denmark or Germany.

Wind Turbines:
Developments in wind turbine technology are rapid and ongoing. Most turbines fit the description shown in the picture above. In recent years, developments such as variable slip, variable speed and DFIG generators have been adopted by most manufacturers. Some manufacturers have eliminated the gearbox and instead used large radius multipole generators. The major phenomenon has been the relentless increase in scale, e.g. in 1992 the typical size of wind turbine was 250kW, by 1996 600kW was standard, and by 2006, windfarms are installing 3MW turbines. The height of turbines has increased in tandem with output power with blade tip heights reaching 145m for 3MW turbines. (Offshore turbines tend to be larger, e.g. Ireland's only offshore windfarm at Arklow used 7x3.5MW turbines.)

Development of wind generation in Ireland
From 1992, when the first windfarm was connected at Bellacorick, to 2003, just 166MW was connected. By 2003, a total 1200MW was either connected or queuing to get connected.

Up to 2003 applications were being connected in sequence on a "first come, first served" basis. This unplanned process was leading to erratic system development and potential huge inefficiencies in network structure. In addition the sheer volume proposed was about to impact on system stability and was of serious concern to National Grid (TSO). As a consequence, DSO (ESB Networks) and TSO made a joint submission to the Commission for Energy Regulation (CER) proposing a moratorium on connection offers pending a full review of system stability and connection issues.

The CER imposed a moratorium from December 2003 to December 2004. During this period, new procedures were developed to address system issues and a new process for handling applications was put in place, essentially a move from individual to a group processing regime. During the moratorium (12 months) the queue of applications increased from 422MW to 2295MW.

Both DSO and TSO process applications and make connection offers based on the connection method and established system boundaries. Applicants are free to make their applications to either TSO or DSO. However, depending on the size and suitability of connection methods, the system operators will exchange applications as appropriate.

Group processing
The CER directed in December 2004 that all new applications were to be processed by means of a group processing regime. The aim was to make quick inroads to the backlog of connection applications while ensuring efficient connection methods and removing earlier issues of "interacting" connection offers. In addition the CER introduced the "Gate" system whereby tranches of applicants in the queue were deemed eligible for connection offers, selected by application completion date. The CER also introduced a standard pricing policy.

Renewable Energy Gates 1 and 2
What is called the "Gate 1" phase of renewable energy included all applications complete prior to 3rd December 2003 and the processing of these applications continued up to April 2006. A draft direction on the Gate 2 process was issued by CER on 21st April 2006. In summary, the new rules for eligibility of connection offers are:

1. The first 500MW of the queue to be a guaranteed connection offer.
2. System optimisation (grouping) to be implemented, whereby all other applicants in the queue will be considered for grouping with applicants the first 500MW and where such grouping results in a least cost technically acceptable solution

The process of invoicing and assessing applications in the first 500MW began in April 2006 following the CER draft direction. Processing and assessing the remainder of applicants will begin following CER's final direction, which is expected in June. The scale of the task in assessing the applications is unprecedented -- over 210 applicants totalling 3000MW must be considered and in a very short timeframe. This represents a processing volume which is 400%- 500% greater than Gate1 and must be completed in a shorter time frame. CER has directed that all successful applicants be identified within 2 months and all offers will be issued within 12 months. The task of identifying successful applicants lies with DSO. Offers of connection will be made by DSO and TSO as appropriate.

The Network Investment Team
Processing of applications is carried out in ESB Networks by Network Investments, Asset Management. The team charged with the responsibility of managing the applications from the wind farms were initially lead by Sheila O'Connor and latterly by Jerry O'Donoghue and included Sandie Madden, Emma McAleese and Deirdre Pender. They carried out sterling work in processing this heavy work load and ensuring that the connection offers were issued to all the successful applicants.

The coming twelve months will see a further step change in the level of applications for wind connections under Gate 2. This work load will present a considerable challenge to the Wind Generation Team. They will now be lead by Tony Hearne who has recently been appointed as Generation Planning Manager. EM